Bidirectional forwarding detection control packet to indicate maintenance mode operation

ABSTRACT

A first network device may determine to transition to a maintenance mode. The first network device may transmit, to a second network device, a bidirectional forwarding detection (BFD) control packet that includes an indication that the first network device is in the maintenance mode.

BACKGROUND

Bidirectional forwarding detection (BFD) protocol may be used to detectfaults on a link between two network devices. Network devices mayexchange BFD control packets at a particular time interval and/or basedon a request for a BFD control packet being transmitted. A networkdevice may detect a fault associated with a link based on whether a BFDcontrol packet (or a quantity of BFD control packets) is received fromanother network device associated with the link within the timeinterval, based on whether a BFD control packet is received in responseto a request, and/or the like.

SUMMARY

According to some implementations, a method may include determining, bya first network device, to transition to a maintenance mode; andgenerating, by the first network device, a bidirectional forwardingdetection (BFD) control packet that includes a diagnostic code fieldthat indicates that the first network device is in the maintenance mode;and transmitting, by the first network device and to a second networkdevice, the BFD control packet to permit the second network device toperform an action based on the diagnostic code field that indicates thatthe first network device is in the maintenance mode.

According to some implementations, a first network device may includeone or more memories and one or more processors to receive, from asecond network device, a BFD control packet that includes an indicationthat the second network device is in a maintenance mode; process the BFDcontrol packet to determine the indication that the second networkdevice is in the maintenance mode; and perform, based on the indicationthat the second network device is in the maintenance mode, one or moreactions associated with a link between the first network device and thesecond network device.

According to some implementations, a non-transitory computer-readablemedium may store one or more instructions. The one or more instructions,when executed by one or more processors of a first network device maycause the one or more processors to determine to transition to amaintenance mode; and transmit, to a second network device, a BFDcontrol packet that includes an indication that the first network deviceis in the maintenance mode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are diagrams of one or more example implementationsdescribed herein.

FIG. 2 is a diagram of an example environment in which systems and/ormethods described herein may be implemented.

FIGS. 3A and 3B are diagrams of example components of one or moredevices of FIG. 2.

FIGS. 4-6 are flowcharts of example processes for bidirectionalforwarding detection (BFD) control packet indication of maintenance modeoperation.

DETAILED DESCRIPTION

The following detailed description of example implementations refers tothe accompanying drawings. The same reference numbers in differentdrawings may identify the same or similar elements.

A network deployment may include a plurality of network devices that arecommunicatively connected via one or more links. The network devices mayimplement one or more networking and/or routing protocols over thelinks, such as border gate protocol (BGP), open shortest path first(OSPF), intermediate system to intermediate system (IS-IS) protocol,and/or the like.

In some cases, a network device may enter a maintenance mode so thatmaintenance (e.g., software and/or firmware updates, bug fixes,configuration updates, and/or the like) may be performed on the networkdevice. However, some networking protocols, such as BGP and/or otherexterior gateway protocols, may not provide a mechanism to divertforwarding plane traffic away from the network device while the networkdevice is in the maintenance mode. As a result, these networkingprotocols may need to be deactivated and/or the links associated withthe network device may need to be brought down in order to divertforwarding plane traffic away from the network device while the networkdevice is in the maintenance mode. This may result in frequent routingtable updates, forwarding information base updates, and/or other updatesin the network deployment to remove the links while the network deviceis in the maintenance mode and to add the links back after the networkdevice is transitioned back into an active mode. This may causeincreased consumption of processing, memory, and/or network resources,may cause delays in forwarding plane traffic forwarding, may causeforwarding plane traffic to be dropped, and/or the like.

According to some implementations described herein, a network device mayuse a bidirectional forwarding detection (BFD) control packet toindicate to other network devices that the network device is in amaintenance mode. In some implementations, the network device maytransmit a BFD control packet to another network device. The BFD controlpacket may include a diagnostic code field, which may be used toindicate a change in session diagnostic parameter of a BFD session ofthe network device. The network device may configure the diagnostic codefield to include a particular value such that the diagnostic code fieldindicates that the network device is in the maintenance mode.

The other network device may identify the particular value in thediagnostic code field and may perform one or more actions associatedwith a link between the network device and the other network device todivert forwarding plane traffic away from the network device while thenetwork device is in the maintenance mode, such as increasing an OSPFlink cost of the link, increasing a route cost of one or more routesthat includes the link, decreasing a BGP local preference of one or moreroutes that includes the link, and/or the like.

In this way, the network device may use the diagnostic code field in theBFD control packet to divert traffic away from the network device whilethe network device is in the maintenance mode and without deactivatingother network protocols or bringing down the links associated with thenetwork device. This decreases consumption of processing, memory, and/ornetwork resources, decreases delays in forwarding plane trafficforwarding, decreases the likelihood of forwarding plane traffic beingdropped, and/or the like as a result of the network device being in themaintenance mode.

FIGS. 1A and 1B are diagrams of one or more example implementations 100described herein. As shown in FIGS. 1A and 1B, example implementation(s)100 may include communication between a plurality of network devices,such as network device 1 and network device 2. In some implementations,network device 1 and network device 2 may be included in a networkdeployment and may be communicatively connected by one or more links. Insome implementations, example implementation(s) 100 may include agreater quantity of network devices.

As shown in FIG. 1A, and by reference number 102, network device 1 maydetermine to transition to a maintenance mode. In some implementations,the maintenance mode may include an operational mode in which networkdevice 1 does not forward forwarding plane traffic in the networkdeployment. The maintenance mode may further include an operational modein which software and/or firmware updates may be performed on networkdevice 1, debugging and/or troubleshooting may be performed on networkdevice 1, control plane and/or forwarding plane configuration updatesmay be performed on network device 1, and/or the like.

In some implementations, network device 1 may determine to transition tothe maintenance mode based on receiving an instruction to transition tothe maintenance mode. For example, the instruction may be provided asinput to network device 1 by a user, may be provided via a link fromanother network device (e.g., network device 2 and/or another networkdevice), and/or the like. In some implementations, network device 1 maydetermine to transition to the maintenance mode based on detecting anevent, such as a fault associated with network device 1 (e.g., a controlplane or forwarding plane fault, a processing system fault, and/or thelike), a fault associated with a link associated with network device 1,and/or the like.

As further shown in FIG. 1A, and by reference number 104, network device1 may generate and transmit a BFD control packet that indicates thatnetwork device 1 is in the maintenance mode. In some implementations,network device 1 may generate and transmit the BFD control packet basedon determining to transition to the maintenance mode. In someimplementations, network device 1 may transmit the BFD control packet tonetwork device 2 and/or other network devices in the network deploymentto which network device 1 is communicatively connected via a link.

In some implementations, the BFD control packet may be transmitted aspart of a BFD session associated with network device 1 and networkdevice 2. In this case, network device 1 may transmit the BFD controlpacket based on a time interval for transmitting BFD control packets inthe BFD session. Moreover, network device 1 may continue to transmit BFDcontrol packets that indicate that network device 1 is in themaintenance mode while network device 1 continues to operate in themaintenance mode.

In some implementations, network device 1 may configure a diagnosticcode field, included in the BFD control packet, to indicate that networkdevice 1 is in the maintenance mode. For example, network device 1 mayconfigure the diagnostic code field to include a particular value thatindicates that network device 1 is in the maintenance mode. Theparticular value may function as an overload indicator (e.g., mayindicate that overload is enabled on network device 1). The overloadindicator may be an indication that network device 1 cannot processadditional forwarding plane traffic and that forwarding plane trafficshould be redirected away from network device 1. In someimplementations, network device 1 may use a diagnostic code fieldreserved value for the particular value, in which case the particularvalue may be represented by one or more bits associated with thereserved value.

Network device 2 may receive the BFD control packet and may process theBFD control packet to identify the diagnostic code field in the BFDcontrol packet, and to identify the particular value included in thediagnostic control field. Network device 2 may be configured todetermine that the particular value is an indicator that network device1 is in the maintenance mode.

As further shown in FIG. 1A, and by reference number 106, network device2 may perform one or more actions based on the BFD control packet. Inparticular, network device 2 may perform one or more actions to divertforwarding plane traffic away from the link between network device 1 andnetwork device 2 based on determining that the BFD control packetindicates that network device 1 is in the maintenance mode.

In some implementations, the one or more actions may include setting anoverload detected parameter, associated with the BFD session of thenetwork device 2, to a particular value. In this case, other networkingprotocols operating on network device 2 that are clients of the BFDsession (e.g., IS-IS protocol, OSPF protocol, BGP, and/or the like) mayidentify the particular value and perform one or more actions.

For example, the OSPF protocol operating on network device 2 mayincrease an OSPF link cost of the link between network device 1 andnetwork device 2 such that the increased OSPF link cost causes networkdevice 2 to generate routes that do not include the link. In this case,network device 2 may transmit an indication of the increased OSPF linkcost to other network devices in the network deployment such that theother network devices may generate routes that do not include the link.

As another example, network device 2 may increase a route cost of one ormore routes that include the link between network device 1 and networkdevice 2, such that the increased route cost causes network device 2 toavoid routing forwarding plane traffic using the one or more routes(e.g., to route the forwarding plane traffic via alternate routes thatdo not include the one or more routes). In this case, network device 2may transmit an indication of the increased route cost of the one ormore routes to other network devices in the network deployment such thatthe other network devices route forwarding plane traffic via alternateroutes.

As another example, a routing protocol operating on network device 2 maydecrease a BGP local preference of one or more routes that include thelink between network device 1 and network device 2 such that thedecreased BGP local preference causes network device 2 to avoid routingforwarding plane traffic using the one or more routes (e.g., to routethe forwarding plane traffic via alternate routes that do not includethe one or more routes). In this case, network device 2 may transmit anindication of the decreased BGP local preference of the one or moreroutes to other network devices in the network deployment such that theother network devices route forwarding plane traffic via alternateroutes.

In some implementations, network device 1 may subsequently transitionout of the maintenance mode and into an active mode (e.g., a mode inwhich network device 1 forwards forwarding plane traffic in the networkdeployment). In this case, network device 1 may generate and transmitanother BFD control packet to network device 2 and/or other networkdevices, where the other BFD control packet indicates that networkdevice 1 is no longer in the maintenance mode. For example, networkdevice 1 may generate the other BFD control packet such that adiagnostic code field, included in the BFD control packet, includes aparticular value that indicates that network device 1 is no longer inthe maintenance mode. In this case, the particular value may include a 0value associated with a No Diagnostic indicator or another value thatmay indicate that network device 1 is no longer in the maintenance mode.

Network device 2 may receive the other BFD control packet, may identifythe particular value in the diagnostic control field, and may determinethat the particular value indicates that network device 1 is no longerin the maintenance mode. In this case, network device 2 may perform oneor more actions to cause forwarding plane traffic to be routed via thelink between network device 1 and network device 2. For example, networkdevice 2 may set the overload detected parameter, associated with theBFD session of the network device 2, to a particular value thatindicates that an overload associated with network device 1 is notdetected. As another example, network device 2 may decrease the OSPFlink cost of the link between network device 1 and network device 2. Asanother example, network device 2 may decrease a route cost of the oneor more routes that include the link between network device 1 andnetwork device 2. As another example, network device 2 may increase theBGP route preference of the one or more routes that include the linkbetween network device 1 and network device 2.

FIG. 1B illustrates an example BFD control packet format. The versionfield (Vers) may identify a version number of BFD associated with theBFD session of network device 1 and network device 2. The diagnosticcode field (Diag) may identify a reason for a change in sessiondiagnostic parameter of the BFD session. This field may be used toindicate that a network device is in a maintenance mode (e.g., byincluding a particular value associated with a maintenance mode oroverload associated with the network device). The state field (Sta) mayindicate a current state of the BFD session. The poll field (P) may beused to request verification of connectivity on the link between networkdevice 1 and network device 2.

The final field (F) may be used to respond to a BFD control packet inwhich the poll field is set to request verification of connectivity. Thecontrol plane independent field (C) may indicate whether the BFD sessionis implemented in a forwarding plane and can continue to functionthrough disruptions in the control plane. The authentication presentfield (A) may indicate whether the BFD session is to be authenticated.The demand mode field (D) may indicate whether the BFD session is tooperate in demand mode, in which case BFD control packets may beexchanged based on requests for the BFD control packets. The multipoint(M) field may indicate whether any point-to-multipoint extensions areactive for the BFD session.

The detection time multiplier field (Detect Mult) may identify aparticular time value by which a time interval for exchanging BFDcontrol packets is to be multiplied. The length field may identify alength of the BFD control packet in bytes. The my discriminator fieldmay identify a unique nonzero discriminator value that may be used todemultiplex a plurality of BFD sessions. The your discriminator fieldmay be used to reflect back a received value in a my discriminatorfield. The desired minimum transmit interval field (Desired Min TxInterval) may identify a minimum time interval for transmitting BFDcontrol packets for the BFD session.

The required minimum receive interval (Required Min RX Interval) fieldmay identify a minimum time interval between received BFD Controlpackets that network device 1 or network device 2 is capable ofsupporting. The required minimum echo receive interval (Required MinEcho RX Interval) field may identify a minimum time interval betweenreceived BFD Echo packets that network device 1 or network device 2 iscapable of supporting.

In this way, network device 1 may transmit a BFD control packet tonetwork device 2, which may include a diagnostic code field that may beused to indicate a change in session diagnostic parameter of a BFDsession of network device 1. Network device 1 may configure thediagnostic code field to include a particular value such that thediagnostic code field indicates that the network device is in themaintenance mode. Network device 2 may identify the particular value inthe diagnostic code field and may perform one or more actions associatedwith a link between network device 1 and network device 2 to divertforwarding plane traffic away from network device 1 while network device1 is in the maintenance mode, without network device 1 having todeactivate other network protocols or bring down the link. Thisdecreases consumption of processing, memory, and/or network resources,decreases delays in forwarding plane traffic forwarding, decrease thelikelihood of forwarding plane traffic being dropped, and/or the like asa result of network device 1 being in the maintenance mode.

As indicated above, FIGS. 1A and 1B are provided merely as one or moreexamples. Other examples may differ from what is described with regardto FIGS. 1A and 1B.

FIG. 2 is a diagram of an example environment 200 in which systemsand/or methods described herein may be implemented. As shown in FIG. 2,environment 200 may include one or more network devices 210-1 through210-n (n≥1) (hereinafter referred to collectively as “network devices210,” and individually as “network device 210”) and a network 220.Devices of environment 200 may interconnect via wired connections,wireless connections, or a combination of wired and wirelessconnections. In some implementations, network devices 210 may be linkedand/or connected together to form a high-availability cluster. In someimplementations, the high-availability cluster may include a pluralityof nodes (e.g., two or more nodes) that are implemented by networkdevices 210.

Network device 210 includes one or more devices capable of receiving,providing, storing, generating, and/or processing information. In someimplementations, network device 210 may include a firewall, a router, agateway, a switch, a bridge, a wireless access point, a base station(e.g., eNodeB, NodeB, gNodeB, and/or the like), and/or the like. In someimplementations, network device 210 may be implemented as a physicaldevice implemented within a housing, such as a chassis. In someimplementations, network device 210 may be implemented as a virtualdevice implemented by one or more computer devices of a cloud computingenvironment or a data center.

In some implementations, a network device 210 may determine totransition to a maintenance mode, may generate a BFD control packet thatincludes a diagnostic code field that indicates that the network device210 is in the maintenance mode, may transmit, to another network device210, the BFD control packet to permit the other network device 210 toperform an action based on the diagnostic code field that indicates thatthe network device 210 is in the maintenance mode, and/or the like. Insome implementations, the other network device 210 may process the BFDcontrol packet to determine the indication that the network device 210is in the maintenance mode and may perform, based on the indication thatthe network device 210 is in the maintenance mode, one or more actionsassociated with the link.

Network 220 includes one or more wireless networks. For example, network220 may include a cellular network (e.g., a long-term evolution (LTE)network, a code division multiple access (CDMA) network, a 3G network, a4G network, a 5G network, another type of cellular network, and/or thelike), a wireless local area network (WLAN) (e.g., a Wi-Fi network, anunlicensed spectrum wireless network, and/or the like), a wirelesspeer-to-peer (P2P) network (e.g., Wi-Fi direct, Bluetooth, and/or thelike), and/or the like, and/or a combination of these or other types ofnetworks.

The number and arrangement of devices and networks shown in FIG. 2 areprovided as an example. In practice, there may be additional devicesand/or networks, fewer devices and/or networks, different devices and/ornetworks, or differently arranged devices and/or networks than thoseshown in FIG. 2. Furthermore, two or more devices shown in FIG. 2 may beimplemented within a single device, or a single device shown in FIG. 2may be implemented as multiple, distributed devices. Additionally, oralternatively, a set of devices (e.g., one or more devices) ofenvironment 200 may perform one or more functions described as beingperformed by another set of devices of environment 200.

FIGS. 3A and 3B are diagrams of example components of one or moredevices of FIG. 2. FIG. 3A is a diagram of example components of adevice 300. In some implementations, device 300 may correspond to device210. In some implementations, device 210 may include one or more devices300 and/or one or more components of device 300. As shown in FIG. 3A,device 300 may include a bus 305, a processor 310, a memory 315, astorage component 320, an input component 325, an output component 330,and a communication interface 335.

Bus 305 includes a component that permits communication among thecomponents of device 300. Processor 310 is implemented in hardware,firmware, or a combination of hardware and software. Processor 310 takesthe form of a central processing unit (CPU), a graphics processing unit(GPU), an accelerated processing unit (APU), a microprocessor, amicrocontroller, a digital signal processor (DSP), a field-programmablegate array (FPGA), an application-specific integrated circuit (ASIC), oranother type of processing component. In some implementations, processor310 includes one or more processors capable of being programmed toperform a function. Memory 315 includes a random access memory (RAM), aread only memory (ROM), and/or another type of dynamic or static storagedevice (e.g., a flash memory, a magnetic memory, and/or an opticalmemory) that stores information and/or instructions for use by processor310.

Storage component 320 stores information and/or software related to theoperation and use of device 300. For example, storage component 320 mayinclude a hard disk (e.g., a magnetic disk, an optical disk, amagneto-optic disk, and/or a solid state disk), a compact disc (CD), adigital versatile disc (DVD), a floppy disk, a cartridge, a magnetictape, and/or another type of non-transitory computer-readable medium,along with a corresponding drive.

Input component 325 includes a component that permits device 300 toreceive information, such as via user input (e.g., a touch screendisplay, a keyboard, a keypad, a mouse, a button, a switch, and/or amicrophone). Additionally, or alternatively, input component 325 mayinclude a sensor for sensing information (e.g., a global positioningsystem (GPS) component, an accelerometer, a gyroscope, and/or anactuator). Output component 330 includes a component that providesoutput information from device 300 (e.g., a display, a speaker, and/orone or more light-emitting diodes (LEDs)).

Communication interface 335 includes a transceiver-like component (e.g.,a transceiver and/or a separate receiver and transmitter) that enablesdevice 300 to communicate with other devices, such as via a wiredconnection, a wireless connection, or a combination of wired andwireless connections. Communication interface 335 may permit device 300to receive information from another device and/or provide information toanother device. For example, communication interface 335 may include anEthernet interface, an optical interface, a coaxial interface, aninfrared interface, a radio frequency (RF) interface, a universal serialbus (USB) interface, a Wi-Fi interface, a cellular network interface, orthe like.

Device 300 may perform one or more processes described herein. Device300 may perform these processes based on processor 310 executingsoftware instructions stored by a non-transitory computer-readablemedium, such as memory 315 and/or storage component 320. Acomputer-readable medium is defined herein as a non-transitory memorydevice. A memory device includes memory space within a single physicalstorage device or memory space spread across multiple physical storagedevices.

Software instructions may be read into memory 315 and/or storagecomponent 320 from another computer-readable medium or from anotherdevice via communication interface 335. When executed, softwareinstructions stored in memory 315 and/or storage component 320 may causeprocessor 310 to perform one or more processes described herein.Additionally, or alternatively, hardwired circuitry may be used in placeof or in combination with software instructions to perform one or moreprocesses described herein. Thus, implementations described herein arenot limited to any specific combination of hardware circuitry andsoftware.

The number and arrangement of components shown in FIG. 3A are providedas an example. In practice, device 300 may include additionalcomponents, fewer components, different components, or differentlyarranged components than those shown in FIG. 3A. Additionally, oralternatively, a set of components (e.g., one or more components) ofdevice 300 may perform one or more functions described as beingperformed by another set of components of device 300.

FIG. 3B is a diagram of example components of a device 350. In someimplementations, device 350 may correspond to device 210. In someimplementations, device 210 may include one or more devices 350 and/orone or more components of device 350. As shown in FIG. 3B, device 350may include one or more input components 355-1 through 355-B (B≥1)(hereinafter referred to collectively as input components 355, andindividually as input component 355), a switching component 360, one ormore output components 365-1 through 365-C (C≥1) (hereinafter referredto collectively as output components 365, and individually as outputcomponent 365), and a controller 370.

Input components 355 may be points of attachment for physical links andmay be points of entry for incoming traffic, such as packets. Inputcomponent 355 may process incoming traffic, such as by performing datalink layer encapsulation or decapsulation. In some implementations,input component 355 may send and/or receive packets. In someimplementations, input component 355 may include an input line card thatincludes one or more packet processing components (e.g., in the form ofintegrated circuits), such as one or more interface cards (IFCs), packetforwarding components, line card controller components, input ports,processors, memories, and/or input queues. In some implementations,device 350 may include one or more input components 355.

Switching component 360 may interconnect input components 355 withoutput components 365. In some implementations, switching component 360may be implemented via one or more crossbars, via busses, and/or withshared memories. The shared memories may act as temporary buffers tostore packets from input components 355 before the packets areeventually scheduled for delivery to output components 365. In someimplementations, switching component 360 may enable input components355, output components 365, and/or controller 370 to communicate.

Output component 365 may store packets and may schedule packets fortransmission on output physical links. Output component 365 may supportdata link layer encapsulation or decapsulation, and/or a variety ofhigher-level protocols. In some implementations, output component 365may send packets and/or receive packets. In some implementations, outputcomponent 365 may include an output line card that includes one or morepacket processing components (e.g., in the form of integrated circuits),such as one or more IFCs, packet forwarding components, line cardcontroller components, output ports, processors, memories, and/or outputqueues. In some implementations, device 350 may include one or moreoutput components 365. In some implementations, input component 355 andoutput component 365 may be implemented by the same set of components(e.g., an input/output component may be a combination of input component355 and output component 365).

Controller 370 includes a processor in the form of, for example, a CPU,a GPU, an APU, a microprocessor, a microcontroller, a DSP, an FPGA, anASIC, and/or another type of processor. The processor is implemented inhardware, firmware, or a combination of hardware and software. In someimplementations, controller 370 may include one or more processors thatcan be programmed to perform a function.

In some implementations, controller 370 may include a RAM, a ROM, and/oranother type of dynamic or static storage device (e.g., a flash memory,a magnetic memory, an optical memory, and/or the like) that storesinformation and/or instructions for use by controller 370.

In some implementations, controller 370 may communicate with otherdevices, networks, and/or systems connected to device 300 to exchangeinformation regarding network topology. Controller 370 may createrouting tables based on the network topology information, createforwarding tables based on the routing tables, and forward theforwarding tables to input components 355 and/or output components 365.Input components 355 and/or output components 365 may use the forwardingtables to perform route lookups for incoming and/or outgoing packets.

Controller 370 may perform one or more processes described herein.Controller 370 may perform these processes in response to executingsoftware instructions stored by a non-transitory computer-readablemedium. A “computer-readable medium” as used herein is a non-transitorymemory device. A memory device includes memory space within a singlephysical storage device or memory space spread across multiple physicalstorage devices.

Software instructions may be read into a memory and/or storage componentassociated with controller 370 from another computer-readable medium orfrom another device via a communication interface. When executed,software instructions stored in a memory and/or storage componentassociated with controller 370 may cause controller 370 to perform oneor more processes described herein. Additionally, or alternatively,hardwired circuitry may be used in place of or in combination withsoftware instructions to perform one or more processes described herein.Thus, implementations described herein are not limited to any specificcombination of hardware circuitry and software.

The number and arrangement of components shown in FIG. 3B are providedas an example. In practice, device 350 may include additionalcomponents, fewer components, different components, or differentlyarranged components than those shown in FIG. 3B.

FIG. 4 is a flow chart of an example process 400 for transmitting a BFDcontrol packet to indicate maintenance mode operation. In someimplementations, one or more process blocks of FIG. 4 may be performedby a first network device (e.g., network device 210, device 300, device350, and/or the like). In some implementations, one or more processblocks of FIG. 4 may be performed by another device or a group ofdevices separate from or including the first network device, such asanother network device and/or the like.

As shown in FIG. 4, process 400 may include determining to transition toa maintenance mode (block 410). For example, the first network device(e.g., using processor 310, memory 315, storage component 320, inputcomponent 325, output component 330, communication interface 335, inputcomponent 355, switching component 360, output component 365, controller370, and/or the like) may determine to transition to a maintenance mode,as described above.

As further shown in FIG. 4, process 400 may include generating a BFDcontrol packet that includes a diagnostic code field that indicates thatthe first network device is in the maintenance mode (block 420). Forexample, the first network device (e.g., using processor 310, memory315, storage component 320, input component 325, output component 330,communication interface 335, input component 355, switching component360, output component 365, controller 370, and/or the like) may generatea BFD control packet that includes a diagnostic code field thatindicates that the first network device is in the maintenance mode, asdescribed above.

As further shown in FIG. 4, process 400 may include transmitting, to asecond network device, the BFD control packet to permit the secondnetwork device to perform an action based on the diagnostic code fieldthat indicates that the first network device is in the maintenance mode(block 430). For example, the first network device (e.g., usingprocessor 310, memory 315, storage component 320, input component 325,output component 330, communication interface 335, input component 355,switching component 360, output component 365, controller 370, and/orthe like) may transmit, to a second network device, the BFD controlpacket to permit the second network device to perform an action based onthe diagnostic code field that indicates that the first network deviceis in the maintenance mode, as described above.

Process 400 may include additional implementations, such as any singleimplementation or any combination of implementations described belowand/or in connection with one or more other processes describedelsewhere herein.

In a first implementation, the diagnostic code field includes aparticular value, associated with an overload enabled indicator,indicating that the first network device is in the maintenance mode. Ina second implementation, alone or in combination with the firstimplementation, process 400 includes determining to transition from themaintenance mode to an active mode; generating another BFD controlpacket that includes an indication that the first network device is inthe active mode; and transmitting, to the second network device, theother BFD control packet to permit the second network device to performan action based on the indication that the first network device is inthe active mode. In a third implementation, alone or in combination withone or more of the first and second implementations, the indication thatthe first network device is in the active mode comprises a particularvalue in the diagnostic code field included in the other BFD controlpacket, wherein the particular value is associated with a no diagnosticindicator.

Although FIG. 4 shows example blocks of process 400, in someimplementations, process 400 may include additional blocks, fewerblocks, different blocks, or differently arranged blocks than thosedepicted in FIG. 4. Additionally, or alternatively, two or more of theblocks of process 400 may be performed in parallel.

FIG. 5 is a flow chart of an example process 500 for receiving a BFDcontrol packet to indicate maintenance mode operation. In someimplementations, one or more process blocks of FIG. 5 may be performedby a first network device (e.g., network device 210, device 300, device350, and/or the like). In some implementations, one or more processblocks of FIG. 5 may be performed by another device or a group ofdevices separate from or including the first network device, such asanother network device and/or the like.

As shown in FIG. 5, process 500 may include receiving, from a secondnetwork device, a BFD control packet that includes an indication thatthe second network device is in a maintenance mode (block 510). Forexample, the first network device (e.g., using processor 310, memory315, storage component 320, input component 325, output component 330,communication interface 335, input component 355, switching component360, output component 365, controller 370, and/or the like) may receive,from a second network device, a BFD control packet that includes anindication that the second network device is in a maintenance mode, asdescribed above.

As further shown in FIG. 5, process 500 may include processing the BFDcontrol packet to determine the indication that the second networkdevice is in the maintenance mode (block 520). For example, the firstnetwork device (e.g., using processor 310, memory 315, storage component320, input component 325, output component 330, communication interface335, input component 355, switching component 360, output component 365,controller 370, and/or the like) may process the BFD control packet todetermine the indication that the second network device is in themaintenance mode, as described above.

As further shown in FIG. 5, process 500 may include performing, based onthe indication that the second network device is in the maintenancemode, one or more actions associated with a link between the firstnetwork device and the second network device (block 530). For example,the first network device (e.g., using processor 310, memory 315, storagecomponent 320, input component 325, output component 330, communicationinterface 335, input component 355, switching component 360, outputcomponent 365, controller 370, and/or the like) may perform, based onthe indication that the second network device is in the maintenancemode, one or more actions associated with a link between the firstnetwork device and the second network device, as described above.

Process 500 may include additional implementations, such as any singleimplementation or any combination of implementations described belowand/or in connection with one or more other processes describedelsewhere herein.

In a first implementation, the indication that the second network deviceis in the maintenance mode comprises a particular value in a diagnosticcode field included in the BFD control packet. In a secondimplementation, alone or in combination with the first implementation,the particular value is associated with an overload enabled indicator.In a third implementation, alone or in combination with one or more ofthe first and second implementations, process 500 includes setting anoverload detected parameter, associated with a BFD session of the firstnetwork device, to a particular value. In a fourth implementation, aloneor in combination with one or more of the first through thirdimplementations, process 500 includes increasing an OSPF link cost ofthe link between the first network device and the second network device.

In a fifth implementation, alone or in combination with one or more ofthe first through fourth implementations, process 500 includestransmitting, to a third network device, an indication of the OSPF linkcost based on increasing the OSPF link cost of the link. In a sixthimplementation, alone or in combination with one or more of the firstthrough fifth implementations, process 500 includes increasing a routecost of a route that includes the link between the first network deviceand the second network device. In a seventh implementation, alone or incombination with one or more of the first through sixth implementations,process 500 includes transmitting, to a third network device, anindication of the route cost based on increasing the route cost of theroute.

In an eighth implementation, alone or in combination with one or more ofthe first through seventh implementations, process 500 includesdecreasing a border gateway protocol (BGP) local preference of a routethat includes the link between the first network device and the secondnetwork device. In a ninth implementation, alone or in combination withone or more of the first through eighth implementations, process 500includes transmitting, to a third network device, an indication of theBGP local preference based on decreasing the BGP local preference of theroute.

Although FIG. 5 shows example blocks of process 500, in someimplementations, process 500 may include additional blocks, fewerblocks, different blocks, or differently arranged blocks than thosedepicted in FIG. 5. Additionally, or alternatively, two or more of theblocks of process 500 may be performed in parallel.

FIG. 6 is a flow chart of an example process 600 for transmitting a BFDcontrol packet to indicate maintenance mode operation. In someimplementations, one or more process blocks of FIG. 6 may be performedby a first network device (e.g., network device 210, device 300, device350, and/or the like). In some implementations, one or more processblocks of FIG. 6 may be performed by another device or a group ofdevices separate from or including the first network device, such asanother network device and/or the like.

As shown in FIG. 6, process 600 may include determining to transition toa maintenance mode (block 610). For example, the first network device(e.g., using processor 310, memory 315, storage component 320, inputcomponent 325, output component 330, communication interface 335, inputcomponent 355, switching component 360, output component 365, controller370, and/or the like) may determine to transition to a maintenance mode,as described above.

As further shown in FIG. 6, process 600 may include transmitting, to asecond network device, a BFD control packet that includes an indicationthat the first network device is in the maintenance mode (block 620).For example, the first network device (e.g., using processor 310, memory315, storage component 320, input component 325, output component 330,communication interface 335, input component 355, switching component360, output component 365, controller 370, and/or the like) maytransmit, to a second network device, a BFD control packet that includesan indication that the first network device is in the maintenance mode,as described above.

Process 600 may include additional implementations, such as any singleimplementation or any combination of implementations described belowand/or in connection with one or more other processes describedelsewhere herein.

In a first implementation, the indication that the first network deviceis in the maintenance mode comprises a particular value in a diagnosticcode field included in the BFD control packet. In a secondimplementation, alone or in combination with the first implementation,the particular value is associated with an overload enabled indicator.In a third implementation, alone or in combination with one or more ofthe first and second implementations, process 600 includes determiningto transition from the maintenance mode to an active mode; andtransmitting, to the second network device, another BFD control packetthat includes an indication that the first network device is in theactive mode.

In a fourth implementation, alone or in combination with one or more ofthe first through third implementations, the indication that the firstnetwork device is in the active mode comprises a particular value in adiagnostic code field included in the BFD control packet. In a fifthimplementation, alone or in combination with one or more of the firstthrough fourth implementations, the particular value is associated witha no diagnostic indicator.

Although FIG. 6 shows example blocks of process 600, in someimplementations, process 600 may include additional blocks, fewerblocks, different blocks, or differently arranged blocks than thosedepicted in FIG. 6. Additionally, or alternatively, two or more of theblocks of process 600 may be performed in parallel.

The foregoing disclosure provides illustration and description, but isnot intended to be exhaustive or to limit the implementations to theprecise forms disclosed. Modifications and variations may be made inlight of the above disclosure or may be acquired from practice of theimplementations.

As used herein, the term traffic or content may include a set ofpackets. A packet may refer to a communication structure forcommunicating information, such as a protocol data unit (PDU), a networkpacket, a datagram, a segment, a message, a block, a cell, a frame, asubframe, a slot, a symbol, a portion of any of the above, and/oranother type of formatted or unformatted unit of data capable of beingtransmitted via a network.

As used herein, the term “component” is intended to be broadly construedas hardware, firmware, and/or a combination of hardware and software.

It will be apparent that systems and/or methods described herein may beimplemented in different forms of hardware, firmware, or a combinationof hardware and software. The actual specialized control hardware orsoftware code used to implement these systems and/or methods is notlimiting of the implementations. Thus, the operation and behavior of thesystems and/or methods are described herein without reference tospecific software code—it being understood that software and hardwarecan be designed to implement the systems and/or methods based on thedescription herein.

Even though particular combinations of features are recited in theclaims and/or disclosed in the specification, these combinations are notintended to limit the disclosure of various implementations. In fact,many of these features may be combined in ways not specifically recitedin the claims and/or disclosed in the specification. Although eachdependent claim listed below may directly depend on only one claim, thedisclosure of various implementations includes each dependent claim incombination with every other claim in the claim set.

No element, act, or instruction used herein should be construed ascritical or essential unless explicitly described as such. Also, as usedherein, the articles “a” and “an” are intended to include one or moreitems, and may be used interchangeably with “one or more.” Further, asused herein, the article “the” is intended to include one or more itemsreferenced in connection with the article “the” and may be usedinterchangeably with “the one or more.” Furthermore, as used herein, theterm “set” is intended to include one or more items (e.g., relateditems, unrelated items, a combination of related and unrelated items,etc.), and may be used interchangeably with “one or more.” Where onlyone item is intended, the phrase “only one” or similar language is used.Also, as used herein, the terms “has,” “have,” “having,” or the like areintended to be open-ended terms. Further, the phrase “based on” isintended to mean “based, at least in part, on” unless explicitly statedotherwise. Also, as used herein, the term “or” is intended to beinclusive when used in a series and may be used interchangeably with“and/or,” unless explicitly stated otherwise (e.g., if used incombination with “either” or “only one of”).

What is claimed is:
 1. A method, comprising: determining, by a firstnetwork device, to transition to a maintenance mode; and generating, bythe first network device, a bidirectional forwarding detection (BFD)control packet that includes a diagnostic code field that indicates thatthe first network device is in the maintenance mode; and transmitting,by the first network device and to a second network device, the BFDcontrol packet to permit the second network device to perform an actionbased on the diagnostic code field that indicates that the first networkdevice is in the maintenance mode.
 2. The method of claim 1, wherein thediagnostic code field includes a particular value, associated with anoverload enabled indicator, indicating that the first network device isin the maintenance mode.
 3. The method of claim 1, further comprising:determining to transition from the maintenance mode to an active mode;generating another BFD control packet that includes an indication thatthe first network device is in the active mode; and transmitting, to thesecond network device, the other BFD control packet to permit the secondnetwork device to perform an action based on the indication that thefirst network device is in the active mode.
 4. The method of claim 3,wherein the indication that the first network device is in the activemode comprises: a particular value in the diagnostic code field includedin the other BFD control packet, wherein the particular value isassociated with a no diagnostic indicator.
 5. A first network device,comprising: one or more memories; and one or more processors to:receive, from a second network device, a bidirectional forwardingdetection (BFD) control packet that includes an indication that thesecond network device is in a maintenance mode; process the BFD controlpacket to determine the indication that the second network device is inthe maintenance mode; and perform, based on the indication that thesecond network device is in the maintenance mode, one or more actionsassociated with a link between the first network device and the secondnetwork device.
 6. The first network device of claim 5, wherein theindication that the second network device is in the maintenance modecomprises: a particular value in a diagnostic code field included in theBFD control packet.
 7. The first network device of claim 6, wherein theparticular value is associated with an overload enabled indicator. 8.The first network device of claim 5, wherein the one or more processors,when performing the one or more actions associated with the link betweenthe first network device and the second network device, are to: set anoverload detected parameter, associated with a BFD session of the firstnetwork device, to a particular value.
 9. The first network device ofclaim 5, wherein the one or more processors, when performing the one ormore actions associated with the link between the first network deviceand the second network device, are to: increase an open shortest pathfirst (OSPF) link cost of the link between the first network device andthe second network device.
 10. The first network device of claim 9,wherein the one or more processors, when performing the one or moreactions associated with the link between the first network device andthe second network device, are to: transmit, to a third network device,an indication of the OSPF link cost based on increasing the OSPF linkcost of the link.
 11. The first network device of claim 5, wherein theone or more processors, when performing the one or more actionsassociated with the link between the first network device and the secondnetwork device, are to: increase a route cost of a route that includesthe link between the first network device and the second network device.12. The first network device of claim 11, wherein the one or moreprocessors, when performing the one or more actions associated with thelink between the first network device and the second network device, areto: transmit, to a third network device, an indication of the route costbased on increasing the route cost of the route.
 13. The first networkdevice of claim 5, wherein the one or more processors, when performingthe one or more actions associated with the link between the firstnetwork device and the second network device, are to: decrease a bordergateway protocol (BGP) local preference of a route that includes thelink between the first network device and the second network device. 14.The first network device of claim 13, wherein the one or moreprocessors, when performing the one or more actions associated with thelink between the first network device and the second network device, areto: transmit, to a third network device, an indication of the BGP localpreference based on decreasing the BGP local preference of the route.15. A non-transitory computer-readable medium storing instructions, theinstructions comprising: one or more instructions that, when executed byone or more processors of a first network device, cause the one or moreprocessors to: determine to transition to a maintenance mode; andtransmit, to a second network device, a bidirectional forwardingdetection (BFD) control packet that includes an indication that thefirst network device is in the maintenance mode.
 16. The non-transitorycomputer-readable medium of claim 15, wherein the indication that thefirst network device is in the maintenance mode comprises: a particularvalue in a diagnostic code field included in the BFD control packet. 17.The non-transitory computer-readable medium of claim 16, wherein theparticular value is associated with an overload enabled indicator. 18.The non-transitory computer-readable medium of claim 15, wherein the oneor more instructions, when executed by the one or more processors,further cause the one or more processors to: determine to transitionfrom the maintenance mode to an active mode; and transmit, to the secondnetwork device, another BFD control packet that includes an indicationthat the first network device is in the active mode.
 19. Thenon-transitory computer-readable medium of claim 18, wherein theindication that the first network device is in the active modecomprises: a particular value in a diagnostic code field included in theBFD control packet.
 20. The non-transitory computer-readable medium ofclaim 19, wherein the particular value is associated with a nodiagnostic indicator.